Vp. Kuznetsov et al., Molecular structure of alpha,beta-unsaturated ketones: 2-benzylidenecyclohexanone and some of its derivatives, CRYSTALLO R, 44(2), 1999, pp. 196-203
The molecular structure of 2-benzylidenecyclohexanone is determined by X-ra
y diffraction analysis. The data on molecular structures of alpha,beta-unsa
turated ketones (including chiral 3R,6R-2-arylidene-3-methyl-6-isopropylcyc
lohexanones) with the enone fragment fixed in the s-cis configuration by th
e cyclohexane ring are considered. A characteristic feature of these molecu
lar structures is the acoplanarity of the double bond with both the carbony
l group and the benzene ring. The degree of acoplanarity depends on the nat
ure of substituents in the arylidene and cyclohexanone fragments. The steri
c stress of the studied molecular structures manifests itself in the presen
ce of short intramolecular atomic contacts between the benzene ring and the
cyclic >C(3)HR fragment (where R is hydrogen atom or substituent) and also
in substantial distortions of bond angles at the sp(2) carbon atoms.